Immunotherapy using monoclonal antibodies (mAbs) has emerged as a safe and selective method for the treatment of cancer and other diseases. In particular, the role of monoclonal antibodies in therapies that are based on B-cell depletion, e.g. in the treatment of B-cell malignancies, has expanded since the introduction of rituximab (Rituxan®), an antibody that is directed against the CD20 antigen on the B-cell surface. Numerous studies have confirmed the efficacy of rituximab as a single agent and in combination therapy in low-grade NHL. Frontline therapy with rituximab added to the combination of cyclophosphamide, doxorubicin, vincristine, and prednisolone (CHOP) significantly improves the outcome for patients with advanced-stage follicular lymphoma compared with therapy with CHOP alone (Hiddemann W, et al. Blood 2005; 106: 3725-3732 (2005)). The addition of rituximab to a combination of fludarabine, cyclophosphamide, mitoxantrone (FCM) significantly increases the response rate and prolongs survival as compared with FCM alone in patients with relapsed and refractory follicular and mantle cell lymphomas (Forstpointner R, et al., Blood, 2004; 104: 3064-3071).
However, only a subset of patients responds to therapy and the majority of those eventually relapse following rituximab treatment. Therefore, there is a need to find immunotherapies with higher efficacy than antibodies that are directed against the CD20 antigen (e.g. rituximab).